Black Marks On Painted Wood Siding Shingles

As the blue green algae accumulate they develop a dark hardened outer coating which results in the black stains you see.

Black marks on painted wood siding shingles.

Micro black spots on siding tags. The iron found in galvanized fasteners as well as some window screens and flashings can cause blue or black stains on cedar. The black roof stains are caused by a form of algae that has been around for years typically found in the woods on the north side of trees or on exposed rocks. Black brown or gray stains on roofing products due to debris left on the roof surface such as piles of leaves and organic waste from nearby trees.

These black streaks are unsightly and can diminish the appearance of the entire exterior of the home. Instead use a wood. Some tell us it s from spiders. The algae feed on the limestone in shingles.

Oil based stains actually feed mold. Black stains on vinyl or painted building exterior wall siding may also be mold as our photo shows at above right. The problem is that for many years the only semi transparent wood stains on the market were oil based. Black mold we have all seen wood sided homes that turned that death black color.

In wooded or shaded areas mold is going to present itself insidiously. The algae will worsen and become more noticeable each year trapping moisture and causing premature shingle aging and granule loss. These stains don t respond to oxygen bleach. It is not uncommon for roof shingles to turn black over time.

It just looks bad. But now this black algae is termed a roof shingle algae because of the annoying discoloration on a asphalt shingle roof. The black streaks running down roofs are actually a hardy algae called gloeocapsa magma. Remove black stains from roof shingles to preserve the appearance of your home s roof.

See debris staining and see proximate cause of roof shingle stains.